Select Good for quality (Best takes forever with little improvement in quality)

Choose your amount to suit. For a heavier blur use 100. You might have to test it
and undo a few times to get exactly what looks best on your image.

And here we have the final result. Changing the feather and the blur amount will
change the effect. Experiment with different shaped selections and different amounts
of blur. In some cases you may want to apply the blur more than once.